In a conversation with a friend some years ago, he told me he tries to not make food decisions based on cost. His meaning was that he’s not going to get a 12-inch sandwich simply because the math supports a cost savings.

I get it. It puts him in a position of being conflicted about not wasting the extra food he didn’t need in the first place. That said, if cost is your primary concern, you should always go with a large pizza instead of two mediums.

I’ve always sort of known that in a non-scientific way (haven’t we all?) but I stumbled upon this article on Curiosity.com that supports my tentative insight. It has to do with pi. Not pie. Pi.

It’s simple geometry: the formula for the area of a circle is pi multiplied by the radius squared. That means that the area of a circle gets bigger with the square of its radius — also known as quadratically, rather than linearly. So by doubling the radius of an 8-inch pizza to get a 16-inch pizza, you’re actually quadrupling the area. In other words, you’d need four 8-inch pizzas to equal one 16-inch pizza. We’re guessing your local pizza place doesn’t charge four times more for a large than it does for a small.

In fact, your average pizza place charges a lot less than that. In 2014, Quoctrung Bui of NPR’s Planet Money podcast created a pizza-value calculator that shows you just how much pizza you’re getting for your money. So say, if you were trying to decide between the extra-large 24-inch pizza or two medium 14-inch pizzas, the graph could tell you the extra-large is the way to go. It gets you the same amount of food as roughly three 14-inch pizzas, and yet costs about $18 less.

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Back to my friend and his desire to eat sensibly. He’s right. As pointed out by Curiosity, “less is more” sometimes. If you’re trying to save money and know you can eat your pizza for more than one meal, go with the large. I know that at my house, leftovers rarely go to waste, especially pizza. But you may occasionally have a different scenario. An airport comes to mind, where you KNOW you won’t eat that whole pizza (and putting it in the fridge isn’t an option) but will dang sure try so you don’t waste the money you spent on it. In that situation, order the pan-sized. And I’m talking to myself here, not so much you.